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Best Location ModCon Low Water-

ced48ced48 Member Posts: 383
Any ideas on a good spot to place a LWCO on a wall-hung ModCon? Some have suggested placing it in a cross with the PRV valve, and a vent on the top of the boiler. I think this dead end location might be asking for nuisance problems. I have thought of running a six foot loop, with the control in the top, but it seems like a lot of piping. Seems like there must be a simpler answer.


  • Jean-David BeyerJean-David Beyer Member Posts: 2,532
    good spot to place a LWCO on a wall-hung ModCon

    I have a mod-con (W-M Ultra3) that stands on my garage floor. But if I had ordered the right bracket,, it could have been mounted on the wall.

    As I face the boiler, the return is on the left, the supply is on the right. The near boiler piping is pretty symmetrical. Going up from the left side is a short nipple, a 1x1x3/4 T, an adapter to go up to 1 1/4 inch, and so on, eventually coming to one of the closely-spaced Ts. The M&M probe type LWCO goes into the 3/4" outlet of that T..

    The supply is on the right and the first thing there is a short nipple, a 1x1x3/4 T that goes to a step-up from 1 inch to 1 1/4 inch and so on, eventually getting to the other of the closely spaced Ts. A Street 90 degree elbow goes into the 3/4" outlet of that T, and the Pressure Relief valve goes into the elbow.

    The 3/4 outlets from those Ts are at the same height from the floor.
  • SlimpickinsSlimpickins Member Posts: 314

    I've install dozens of Triangle Tube Solo and Lochivar Knights using the cross method on top of the wall hungs without a hitch. If you pipe your primary loop out of the bottom and have your closely placed tee's or LLH above the boiler you could tee it in slightly about the heat exchanger. But that scenario happened once before I went exclusively with LLH's. Just remember for the PRV you need to 90 up and install the PRV so your discharge is horizontal.

    I've been away from the wall for a couple months working on AC during this hot Colorado summer.  Wish I could do hydronics full time. Did I miss anything?
  • JasonJason Member Posts: 294

    In PA it must be above the heat exchanger and not more than 18" above the het exchanger.
  • Jean-David BeyerJean-David Beyer Member Posts: 2,532
    and not more than 18" above the het exchanger.

    I wonder why that is? As long as it is at least above the heat exchanger, and that there are no valves whatever between the heat exchanger and the PRV, what difference how high it is?

    Is it because the farther away from the boiler it is, the more likely it is to freeze up, so when the aquastats fail on, the ice plug would keep the pressure from opening the PRV? Or that even if it opened, the flow past the ice plug would be too slow until the ice melted?
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